I am building wireframes for a social networking site and I would like to know how does google ads work. Does it read all content of you site and than showing ads on your site or can you set which part of site is important. For example if I have site for car fans and every user has own site where he can put profile of his car. Can I set that it will show different ad in every profile site dependent of brand of described car? tnx P.S.: How difficult is to integrate google ads?